Detachable stair-tread.



,1. w. soon & T. H. GREER.

DETAC HABLE STAIR TREAD.

APPLICATION FILED FEB. 15. 1915.

1,142,372 Patented June 8, 1915.

- y In ventor Jbhn Mllz'am Scott 144 by 772011235 72. 67667 W Att mounted E STATES PAE JOHN WILLIAM SCOTT, OF

DETACHABLE STAIR-TREAD.

Specification of Letters Patent.

Patented June 8, 1915.

Application filed February 15, 1915. Serial No. 8,223.

T all whom it may concern:

Be it known that we, JOHN WILLIAM Sco'r'r and THOMAS H. GREER, citizens of the United States, residing, respectively, at New York city, in the county of New York and State of New York, and South Orange, in the county of Essex and State of New Jersey, have invented new and useful Improvements in Detachable Stair-Treads, of which the following is a specification.

This invention relates to detachable treads for stairs and particularly treads of the type adapted to withstand the severest of traffic conditions both as to wear and to exposure to the elements.

It consists in an improved composite structure adapted to present a non-slipping abrasive tread surface throughout the entire life of the tread unit and wherein the supporting plate for the material provides hardened bearing surfaces on the tread surface and wherein it is effectually protected against dampness and the resulting corrosive action thereof.

The latter feature of protecting the supporting plate, whichordinarily is of steel, is of the utmost importance for the reason that actual use has shown that treads of this general character wherein the more or less fragile abrasive composition has been upon the upper surface of a backing or base plate have proven highly defective for the reason that a large proportion of the base, plates rust out long before the service wears out the tread portions thereof. In consequence, these treads break up for want of proper backing support and have to be replaced. Moreover, when so constructed with the abrasive material upon the upper surface of a bottom or baseplate, when they do properly stand up under use, the treads thereof wear down to the smooth steel. of the base plate which is slippery and therefore dangerous. V The present invention is designed with the primary object of successfully producing a detachable tread unit which will not so deteriorate from the action of the water that so readily collects beneath these detachable treads when they are secured in position on the stair merely by screws or the like, which is the common practice.

A further important result accompanying the improved structure of the present 1nvention is that the non-slip abrasive material is exposed tov the wearing action even after the tread proper thereof has been worn through.

Our present invention accordingly consists in the tread unit as hereinafter described wherein a skeleton supporting plate or frame is employed to overlie the composite abrasive material whereby the former provides a hardened bearing surface for the tread and through which the non-slip abrasive material is extended to the upper surface of the tread portion thereby to combine the non-slip properties of the composite material with the wearing qualities of the steel of the plate.

The invention further consists in the improved composite material employed which is elastic to a desirable degree and works up under pressure to maintain an effective non-slip surface and furthermore is thoroughly rust proof so as to protect the underside of the supporting and bearing plate. v

The described and other features and advantages of the present invention are hereinafter more fully described and shown in the accompanying drawing wherein similar reference characters are applied to the corresponding parts in the several views. Therein- Figure 1 is a plan view of a desirable embodiment of the present invention and Fig. 2 is'a cross sectional View on line 2-2 thereof.

The improved tread, as shown, comprises the skeleton supporting and bearing frame 1 which may desirably be stamped from sheet steel in the form shown so as to form intersecting channel bars 22 with rectangular openings or spaces therebetween and provided on its edges with the finishing and protecting flanges? To the under side of the supporting plate, so formed, is applied the non-slip composite material 4 extended into the spaces between the bars to fill said spaces flush with the upper plane of the bars and tread thereby combining the nonslip abrasive material with the hard bearing steel for the tread surface. The composite material thus covers the entire under surface of the bearing plate with the result that the plate is fully protected from dampness on its under side. Therein lies a valuable feature of the present invention for the reasons hereinbefore given.

A further feature of this invention re sidesin the particular character of the comthe steel so as to fully protect the latter..

Moreover the asphaltum possesses a desirable degreeof elasticity which improves the tread and from which it results that the asphaltum will Work up under pressure of traffic into the space between the bars so as constantly -to maintain an effective non-slip surface. This latter action is further assistedby the form of the bars 2-2 which as shown are curved in cross-section." For improving the non-slipping qualities of the asphaltum we combine therewith suitable granular abrasive material such as carborundum.

; Th disclosed-form of the bars'22 gives a substantial depth of hard bearing metal on edge which in conjunction with the channels formed thereby materially assist in preventingthe; foot slipping thereon and furthermore in accordance with our invenvtionlthese channels are open at the ends thereof so that water willrun over the protecting flange 4 for draining off of water from the tread surface. As will readily be understood the bearing plate of the form shown may be economically stamped or rolled with the channeled bars which give V the maximum bearing depth with the minimum of material.

The proper bond between the bearing plate and the asphaltum' is obtained by molding the asphaltum therewith .in a

heatedstate and as is readily' understood a V the steel and the'asphaltum if desired.

suitable bindermay be interposed between We have thus produced a compositetread having its supporting plate arranged to reinforcethe tread surface and to befully protected from rust by the asphaltum combined therewith thereby to insure of obtaining the maximum wear of the tread and further to insure against slipping by the continued exposure of abrasive material after the tread surface proper has worn through and prior to its being replaced.

Moreover in the structure as shown the I abrasive material is to alargedegreefinclosed and thereby protected by the metal. As many changes could be made in the above construction and -many' apparently widely difierent embodiments of this invention could be made without departing from the scope thereof, it 'is intended thatfall-matter contained herein shall be interpreted as illustrative and not in a limiting sense.

Havmg described our nvention we claim,-

- J '1. A tread surface comprising a thin'meitallic inverted tray-shaped plate supported 7 by an inclosed plastic under filling and perforated to expose said filling 'whichi'fills' the perforationsfflush with thetop surface of theplate; u j 1 2. Atread surface comprising a thin metallic inverted tray-shaped'plate supported by an inclo'sed asphaltumunder filling and perforated to expose said filling which fills the perforations flush with the top surface of the plateand' makes a wa'ter tightunion 1 with the metal.

8. A tread surface comprising a thin metallic inverted tray-shaped plate supported by an inclosed plastic under filling and perforate'd to expose said filling which fills the perforations flush with the top surface of the plate. and the metal between said per;

forations being channeled tojpresenjt' metal' on edge as the bearingsurface';

In testimony whereof we have signed our '7 j names to this specification in the presence of two subscribing witnesses.

JOHN WILLIAM SCOTT;

THOMASH. GREER.-

Copies of this patent may be obta ined forj five cents each, by addressing tlie Commissioner of Patents. 7

. I I V Wa.shi:ngton, 17.0. V I 

